This application claims the priority of German application 198 38 762.8, filed in Germany on Aug. 26, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a spinning machine having a plurality of spinning stations, which each have an arrangement for condensing a drafted fiber strand, which arrangement comprises a transport surface for guiding the fiber strand over a suction slit of a suction device.
A spinning machine of this type is prior art for example in U.S. Pat. No. 5,600,872. In the case of such spinning machines a central suction channel is provided, which extends over all spinning stations, whereby a suction connection is provided for each arrangement for condensing. In particular in the case of long spinning machines, there is the risk that the vacuum at those spinning stations which are further away from the vacuum generating fan falls off, resulting in differences in quality of the yarns to be spun.
It is an object of the present invention to avoid inadmissable differences in underpressure and thus to avoid differences in yarn quality.
This object has been achieved in accordance with the present invention in that a plurality of suction devices, each provided for a respective plurality of spinning stations, are provided, a fan being provided for each of the suction devices.
The suction devices can be provided for a higher or lower number of spinning stations, according to the size of the fans or the form of the spinning machine. As a result of the short path from each fan to the individual spinning stations, throttling losses and underpressure differences are minimized. Thus differences in quality in the yarn to be spun can be reduced to a permissible level.
For the purpose of the present invention, each suction device including its fan is provided for a plurality of spinning stations of both machine sides. For example, a joint fan can be provided for eight spinning stations of each machine side.
In preferred embodiments of the present invention, the suction devices comprise hollow profiles, which are provided with suction slits according to the number of spinning stations being serviced thereby, said hollow profiles serving as sliding guides for sieve belts comprising the transport surfaces.
According to the number of suction devices, including the fan, which are present, a hollow profile is provided for the same number of spinning stations, said hollow profile having for each spinning station a suction slit, but for all spinning stations arranged thereto only one suction opening, which can be connected to a suction tube of the suction device.
The hollow profile, extending along a plurality of spinning stations, can be sealed clamped onto the respective suction tube by means of a snap lock. This serves in particular for the exchange of a sieve belt when it is worn.
In a further development of preferred embodiments of the present invention, a joint used-air channel is provided for all the suction devices. This ensures that the unavoidable suctioned-off fiber fly on the condensing arrangements does not reach the individual components of the spinning machine.
In order to monitor the vacuum, and thus the yarn quality, a pressure measuring device is preferably arranged for each suction tube so that the vacuum can be regulated for the purpose of the invention. In the case of a malfunction, the relevant machine section is shut down.